Solar active powder for fusion powder coating

ABSTRACT

A fusion powder coating useful in forming a coating by fusion of the powder comprising a solar active or a photovoltaic pigment in combination with a resin including a conductive resin and a device for generating electric energy from solar or photo illumination comprising an electrode, a first powder coated layer of an absorptive pigment and a resin, a second powder coated layer of the aforementioned solar active powder, and a protective layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 14/230,343 filed onMar. 31, 2014, which claimed the benefit of U.S. Provisional Application61/814,522 filed on Apr. 22, 2013. The disclosures of these applicationsare hereby incorporated by reference in their entirety.

FIELD AND BACKGROUND OF INVENTION

A fusion or powder coating process is a process in which a coatingpowder is distributed over a substrate and heated. The heated powderfuses to form a continuous film. The substrate may be heated or unheatedwhen the powder is applied, although heat is subsequently supplied froman external source, such as an oven, causes the powder to fuse into acontinuous film. Known processes for applying powder coatingcompositions to a substrate include electrostatic spraying, fluidizedbed coating and hot flocking.

SUMMARY OF INVENTION

A solar active or photovoltaic composition comprising a solar active orphotovoltaic pigment in combination with a resin including a conductiveresin is described. This composition may form a coating upon fusion orheating. The composition itself is formed by blending the solar activeor photovoltaic pigment into a conductive rein, extruding the blend, andgrinding the extruded blend to form a powder. The solar active orphotovoltaic pigment may be strontium phosphor, a solar nano dot, and/ora semiconductor, such as gallium arsenide. The resin may have a Tggreater than about 62° C., a hydroxyl number of about 40 to 45, and/or ahydroxyl equivalent weight of about 1247 to 1403. The conductive resinmay be a phenolic or conjugated polymer, a polymer containing aconductive pigment, or an acrylate rein. An absorptive pigment, such astitanium dioxide, may also be provided.

Another aspect contemplates a device for generating electric energy fromsolar or photo illumination. The device includes an electrode, a firstpowder-coated layer of an absorptive pigment and a resin, a secondpowder-coated layer of a solar active or photovoltaic composition asdescribed above, and a third powder-coated protective layer. Thephotoactive pigment in the second powder-coated layer may includestrontium phosphor and/or phthalocyanine-coated glass flake.

A final aspect contemplates a composition having 55.8% powder coatingresin; 3.5% absorptive pigments, 4.0% organic conjugated solar activematerial, 15.0% titanium dioxide, and 21.7% polymeric isocyanuratecurative. These percentages are based on gravimetric basis, consistentwith the disclosure below.

In view of the foregoing, one embodiment of the invention comprises amethod of manufacturing a solar-active device or component whichgenerates electricity when a coated surface of the device or componentis exposed to actinic, photo, and/or solar energy. The method includesproviding a substrate and applying a first powder coating compositionincluding a first resin base and at least one photovoltaic and/or solaractive pigment in order to form a photoactive layer. An additionalpowder coating composition for forming an absorptive layer may beapplied to the substrate prior to application of the composition neededto form the photoactive layer, thereby interposing the absorptive layerbetween the substrate and the photoactive layer. An optional powdercoating composition may be applied to create a protective layer. Thepowder coating compositions are heated, separately or in combination toform a fused laminate film adhered to the substrate. Still additionalaspects of the method are disclosed in greater detail in the appendedclaims and below.

Thus, further reference is made to the appended claims and descriptionbelow, all of which disclose elements of the invention. While specificembodiments are identified, it will be understood that elements from onedescribed aspect may be combined with those from a separately identifiedaspect. In the same manner, a person of ordinary skill will have therequisite understanding of common processes, components, and methods,and this description is intended to encompass and disclose such commonaspects even if they are not expressly identified herein.

DETAILED DESCRIPTION

Reference will now be made in detail to exemplary embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. It is to be understood that other embodiments may be utilizedand structural and functional changes may be made without departing fromthe respective scope of the invention. Moreover, features of the variousembodiments may be combined or altered without departing from the scopeof the invention. As such, the following description is presented by wayof illustration only and should not limit in any way the variousalternatives and modifications that may be made to the illustratedembodiments and still be within the spirit and scope of the invention.

Any elements described herein as singular can be pluralized (i.e.,anything described as “one” can be more than one). Any species elementof a genus element can have the characteristics or elements of any otherspecies element of that genus. The described configurations, elements orcomplete assemblies and methods and their elements for carrying out theinvention, and variations of aspects of the invention can be combinedand modified with each other in any combination. As used herein, thewords “example” and “exemplary” mean an instance, or illustration. Thewords “example” or “exemplary” do not indicate a key or preferred aspector embodiment. The word “or” is intended to be inclusive rather anexclusive, unless context suggests otherwise. As an example, the phrase“A employs B or C,” includes any inclusive permutation (e.g., A employsB; A employs C; or A employs both B and C). As another matter, thearticles “a” and “an” are generally intended to mean “one or more”unless context suggest otherwise.

One manifestation of the disclosure is a powder coating composition thatis useful for energy absorption to convert natural energy intoelectricity via direct light. This composition can be appliedelectrostatically to various substrates types (such as wood, plastic,metal, concrete, aluminum, etc.) to form a solid over the varioussubstrates types. This technology can be used as a direct replacementfor the solar glass panel technology.

In one embodiment of the invention, a powder suitable for fusion powdercoating as disclosed herein includes a solar active or photovoltaicpigment in a conductive resin matrix. The powder is made by blending thepigment with the resin, curing the resin (e.g., after extrusion) andgrinding the cured resin layer into a powder. In one embodiment, thepigment is blended with the resin in an extruder.

In one embodiment, the disclosure provides a laminate that is made up ofthree powder coated layers. One layer is applied to and carried on aconductive substrate which functions as an electron collector orelectrode. This layer may contain a light-absorptive or reflectivepigment that directs light energy that is incident the laminate to thephotovoltaic or solar active pigments that are contained in a secondlayer that is positioned on the light incident side of the absorptive areflective pigment layer. The photovoltaic/solar active layer isovercoated with a surface layer that functions as a protective coating.In one embodiment, the photovoltaic or solar-active pigment may benanodots. In summary, this platform utilizes absorption pigments andphotoactive materials and, in one embodiment, organic dye photoactivematerials, to convert incident actinic, photo, or solar energy intoelectricity. One embodiment utilizes about 30-45% total pigment loading.

Photoactive Layer

Coatings developed in accordance with this disclosure for making thephotoactive layer may convert the energy of a light source (e.g.,daylight D65/CWF/direct sun light, etc.) into electricity by utilizingphoto or solar active chemical additives that are blended or embedded(e.g., using a master batch) into a powder coating resin matrix that isconductive. In one embodiment the resin matrix for the photoactive layerincludes a resin having a glass transition temperature greater thanabout 60° C., more particularly greater than about 62° C. with (DSC), ahydroxyl (OH) number of about 40-45 and a hydroxyl equivalent weight(nominal), of about 1200 to 1400 and, more particularly, about1247-1403; a hydroxylated polyester resin, such as Rucote 118 from BayerScience Materials, or SP100 or SP400 from Sun Polymers Internationalthat is typified by a hydroxyl number of 42+/−10 (mg KOH/g), and a meltviscosity specification of 8500 (at 200° C.), or a combination thereof.In one embodiment the two resins may be blended at a ratio of about70/30 (first resin to second resin). This produces a more homogenous mixwhen introduced to the additional fillers and additives when mixed andextruded.

The resin system used in the photoactive layer also contains aconductive resin, such as a conjugated resin, in order to electricallyconduct the electrons generated upon exposure of the photoactive pigmentto the underlying layer and the electrode. Examples of conjugatedpolymers include phenolic resins, such as DER 663U from Dow Chemical,GT76013 from Huntsman Master Batch, as well as resins including aconductive pigment such as Cabot 800 Black Pigment or Ferro FE6331, aconductive black pigment. A polymethyl methacrylate polymer may also beused as a conductive resin, such as AG500 from Sun Polymer. Otherexamples of conductive resins includepoly(2-methoxy-5-(3′7′-dimethyloctyloxy)-1,4-phenylene vinylene fromSigma-Aldrich which is a light emitting conjugated polymer of the rigidrod family, poly(3-hexylthiophene-2,5-diyl) electronic grade 99.995%trace metals from Sigma-Aldrich, and zinc phthalocyanine (ZnPc) with 90%zinc from Sigma-Aldrich. In one embodiment, the conductive polymer maybe used in an amount of about 3 to 8% by weight and the non-conductiveresin may be used in an amount of about 5 to 8% by weight. In oneembodiment, platform binder systems for the photoactive layer containsconstituents such as nano particle titanium dioxide, strontium basedphosphors, solar nano dots, and photovoltaic materials that areincorporated within the platform binder system as photoactive pigments.

In one embodiment, the additives and fillers discussed herein areincorporated into the resin and then extruded into a layer that iscured, and the layer is ground to form a solid resin flake, pigment orfusion powder. The powder may have an average particle size of about 25to 35 micron in one embodiment.

In one embodiment, the solar active or photovoltaic or photoactive layermay have the composition shown in Table 1 below. The photoactive orsolar active layer is responsible for collecting and generating photogenerated charged carriers which are transported to collect at oppositeelectrodes. The photoactive pigments can extract energy from the Sun andother lighting resources such as standard Daylight (D65), Cool WhiteFluorescent lighting (CWF) with minimum time required.

TABLE 1 Example: Solar Active Layer* Powder Coating Resin 55.8%Absorption Pigments 3.5% Organic conjugated Solar Active Material 4.0%Titanium Dioxide 15.0% Polymeric Isocyanurate Curative 21.7% Total 100%*SP 033 Sun Chemicals

In one embodiment, the photo or solar active pigments that are suitablefor use in photovoltaic cells are incorporated into the resin for thephotoactive layer alone or in combination with strong absorbers (asillustrated in Table 1 above) such as the absorbers disclosed forincorporation into the absorptive base layer disclosed below. In oneembodiment, the photoactive pigment is incorporated into a platformbinder resin system additionally containing flow additives and curativesand absorption type pigmentation in an extruder. The extruded layer iscured and ground to provide a powder coating material for forming thephotoactive layer. The powder coating can be sprayed on a support,namely the absorptive layer, and heated 15 min. at 375° F. to form thephotoactive coating. In one embodiment, the photoactive layer is about2.5 to 5.0 mils thick in one embodiment of the invention.

Examples of photovoltaic or photoactive materials useful herein include(Si) silicone, (GaAs) gallium-arsenide, (CdTe) cadmium-telluride, (CIS)cadium-indium-selenide, amorphous silicon, polycrystalline siliconeSilicon base powder material increases the conductivity and acts as abarrier to hold the energy. In one embodiment, the photoactive pigmentis obtained by coating a photoactive dye on a semiconductor carrier. Oneadvantageous solar active material prepared by coating magnesiumphthalocyanine on glass flakes such as GF 200 grade. In one embodiment,the photoactive material is a SEMIC (semiconductor) based materialcrushed into powder form less than 9.0 microns and then blended using amaster batch into Ruco 1 18 resin.

The same process may be followed for other photoactive materials at verylow resin to powder ratios, e.g., 98/2 ratio.

Examples of solar active materials include strontium based phosphorssuch as strontium aluminate pigments. These pigments may be producedwith a photoluminescent layer having a fluorescence of 300 to 800 nm on0.687 mm white-based polyester urethane base. Strontium aluminates basephosphors are used in one embodiment and have exciting wavelengths of300 to 450 nm.

The photo responsive fillers can also be introduced in the form ofnanodots. Examples of solar nanodots useful in the invention arenanocrystal semic (semiconductors) with indium tin oxide and an organicsolar active material. In one embodiment, the nanodots have a particlesize of about 1.0 to 2.0 microns and in one embodiment are blended intoa conductive resin blend having a melt viscosity of about 8500 (at 200°)containing a curative such as TGIC in order to obtain solar selectiveabsorption coatings. The photoactive pigment may be incorporated intothe conductive resin blend in an amount of about 0.1 to 0.5% in oneembodiment. In one embodiment, a solar nanodot pigment useful in oneembodiment is made by master batching conductive pigments into apolyurethane resin including TiO₂ and SiO₂ and creating sub dropletshaving an particle size less than about 2 μm. In one embodiment, thesolar active material is present in the solar active layer in an amountof up to about 4% by wt. and more typically about 2.5 to 4.5% by weight.

Absorptive Layer

The absorption of light is required to activate the photoactive pigmentor nanodots in the photoactive layer. The light source can be andactinic source such as direct light such as sunlight/Daylight D65 orconventional generated light such as CWF or Fluorescent.

The layer containing the absorptive pigments and the protective coatinglayer can be made using powder coating compositions that may be madeusing various resins known to the powder fusion coating art includingpolyurethanes, triglycidylisocyanaturate (TGIC) resins, primid resinsystems, epoxy resins, hybrid polyester and epoxy resin combinations(e.g., epoxy, epoxy-polyester) urethane-polyester, TGIC-free polyesterwhich are free of TGIC and acrylic coating materials. Other constituentsinclude curatives, flow aids, degassing agents, catalysts, pigments,modifiers, fillers and charge inhibitors, photoelectric cells, cadiumnanocrystals (cd), nano-carbon type pigments and conjugated polymers.

Examples of absorption pigmentations include V-9415 Yellow, V-9248 Blue,10202 Black Pigments from Ferro and Ellipse Titanium Dioxide Pigment,Monarch 800 Carbon Black from Cabot Industries, strontium aluminatepigments and nano-carbon pigments. The function of these pigments is toreflect light to the solar active pigments where the light produces anelectric voltage in the electrode. The absorptive pigment isincorporated into the base layer in one embodiment in an amount of about3 to 4.5%. However, larger amounts can be used but add to the expense ofthe device. Titanium dioxide is a particularly desirable absorptivefiller. In one embodiment it is used in an amount up to about 16 wt. %in the absorptive layer.

In one embodiment the absorptive layer is a white nanoporous Ti02 basepowder coating at 1-2 mils thick for absorption of incident light.Increasing absorptive layer thickness, ultimately results in increasedlight absorption and energy retainment in the photoactive layer. Anexample of an absorptive pigment layer is provided in Table 2 below:

TABLE 2 Absorptive layer Titanium White Base* Ruco 118 Polyester Resin331 g 46.0% AG300 Acrylic Resin 131 g 18.3% NI2 Polymeric Isocyanatecurative 90.09 g 12.6% MOD 6000 Flow aid 10.16 g 1.42% 104S De-gassingagent 8.04 g 1.12% RCL 960 Titanium dioxide 150.0 g 20.56% Total 100%*Rucote 118—Bayer Science Materials, AG300—Sun Polymer International, NI2—Bayer Science Materials, MOD 6000—Cytec Industries, 104S—Air Products,RCL-960 Titanium—DuPont

Protective Layer

In one embodiment, the top or protective layer has the composition shownin Table 3. Those skilled in the art will recognize that the protectivefunction of this layer can be obtained with other compositions providedthat the protective layer is compatible with the underlying solar activelayer such that it adheres to it without substantially diminishing thelight transmitted to the solar active layer.

TABLE 3 Protective Layer* Ruco 106 Polyester Resin 462 g 81.0% 1 NI2Polymeric Isocyanate 90.09 g 15.8% 2 Mod 6000 Flow aid 10.16 g 1.78% 3104S De-gassing Agent 8.04 g 1.41% 4 Total 570.29 g 100% *Rucote106—Bayer Science Materials, AG300—Sun Polymer International, NI 2—BayerScience Materials, MOD 6000—Cytec Industries, 104S—Air Products, RCL-960Titanium—DuPont

This platform includes pigments that are blended, e.g., using a masterbatch, with other constituents such as resins, curatives and flow aids.The component constituents comprising the admixture are extruded todistribute the constituents to form an extrusion product. Any suitableextruder may be utilize a singe or twin screw mechanism. In oneembodiment, the blended constituents are placed in the extruder hopperand fed via the screw mechanism to the extruder die, preferable withthree to four temperature zones. The zone settings may be respectively60/60/80/140° F. The blended constituents are extruded at about 300 rpmand at a feed rate of about 400 g/min. to form an extrusion product. Theflow aid facilitates blending of constituents in the extrusion product.The extrusion products are fed through chill rolls and cured in an ovensubsequently for about 15 mins at about 375° F.

The photoactive layer is coated with the protective overcoat which maybe a clear coating designed to protect the coatings outdoors. Theprotective layer must be an outdoor resistance layer such aspolyurethane or acrylic base TGIC combination. In one embodiment, theprotective layer is about 2.0 to 4.0 mils in thickness and cured at 15min at 375° F. It protects the underlying layers from ambient air toprevent degradation of the active layer and electrode materials by theeffect of water and oxygen making the photoactive layer photochemicallystable and preserving the active layer.

Quantitative results illustrates this proprietary technique allows us toutilize this eco-friendly solution to preserve energy up to 24 hourswhich will dramatically reduce energy costs. The technology as a powdercoating can be applied on various substrate types such as plastic,metal, aluminum, wood, concrete, paper, cloth, stucco and a host ofother materials to act as a base to generate electricity, examples beingarchitecture buildings, automobiles, mobile phones, or anything whichrequires power usage to operate.

While individual aspects of the invention are recited above, it ispossible to couple specific features and limitations associated with oneaspect to that of another aspect. Further, the functions and actionsassociated with the method aspect may further inform the structuralfeatures of apparatus aspects noted herein. Any of these foregoingfeatures may form the basis for subsequent claims to still furtheraspects of the invention, even though all of those aspects may not beindividually recited herein.

Although the embodiments of this disclosure have been illustrated in theaccompanying drawings and described in the foregoing detaileddescription, it is to be understood that the present disclosure is notto be limited to just the described embodiments, but that theembodiments described herein are capable of numerous rearrangements,modifications and substitutions without departing from the scope of theclaims hereafter. It is, of course, not possible to describe everyconceivable combination of components or methodologies for purposes ofdescribing the present specification, but one of ordinary skill in theart may recognize that many further combinations and permutations of thepresent specification are possible. Each of the components describedabove may be combined or added together in any permutation to define anintroducing device and/or introducing system. Accordingly, the presentspecification is intended to embrace all such alterations, modificationsand variations that fall within the spirit and scope of the appendedclaims. Furthermore, to the extent that the term “includes” is used ineither the detailed description or the claims, such term is intended tobe inclusive in a manner similar to the term “comprising” as“comprising” is interpreted when employed as a transitional word in aclaim. The claims as follows are intended to include all modificationsand alterations insofar as they come within the scope of the claims orthe equivalent thereof.

1. A method of manufacturing a solar-active device capable of generatingelectricity when the a coated surface of the device is exposed toactinic, photo, or solar energy, the method comprising: providing asubstrate; applying a first powder coating composition onto thesubstrate to create a photoactive layer, the first powder coatingcomposition including a first resin base and at least one photovoltaicor solar-active pigment; optionally, applying an optional powder coatingcomposition onto the photoactive layer to create a protective layer; andheating all powder coating composition(s) on the substrate to form afused laminate film adhered to the substrate.
 2. The method according toclaim 1 further comprising applying an additional powder coatingcomposition onto the substrate to create an absorptive layer, theadditional powder coating composition including a second resin base andat least one light-absorptive or reflective pigment, and wherein theadditional powder coating composition is applied to the substrate beforethe first powder coating so that the absorptive layer is interposedbetween the substrate and the photoactive layer.
 3. The method accordingto claim 2 wherein the additional powder coating composition includes aconductive resin.
 4. The method according to claim 2 wherein all of thepowder coating compositions collectively utilize about 30-45% totalpigment loading by weight.
 5. The method according to claim 2 wherein,prior to applying the additional powder coating composition, thelight-absorptive and/or reflective pigment(s) are blended with theadditional resin while the second powder coating composition is beingextruded.
 6. The method according to claim 2 wherein a temperatureduring the heating is maintained at least 375° F.
 7. The methodaccording to claim 2 wherein the heating occurs separately for eachpowder coating composition prior to applying any subsequent powdercomposition(s).
 8. The method according to claim 2 wherein the lightabsorptive and/or reflective pigment(s) are present in the additionalpowder coating composition are collectively between 3% to 4.5% by weightof the second powder composition.
 9. The method according to claim 1wherein the substrate comprises metal or aluminum.
 10. The methodaccording to claim 1 wherein the photoactive layer includes an organicdye photoactive material and/or nanodots.
 11. The method according toclaim 1 wherein, prior to applying the first powder composition, thephotovoltaic and/or solar-active pigment(s) are blended with the firstresin while the first powder coating composition is being extruded. 12.The method according to claim 1 wherein a temperature during the heatingis at least 375° F.
 13. The method according to claim 1 wherein thesubstrate comprises at least one of wood, plastic, metal, concrete, andaluminum.
 14. The method according to claim 1 wherein the heating occursseparately for each powder coating composition prior to applying anysubsequent powder coating composition.
 15. The method according to claim1 wherein photoactive layer is about 2.5 to 5.0 mils thick.
 16. Themethod according to claim 1 wherein the photovoltaic and/or solar-activepigment(s) are present in the first powder coating composition atbetween 2.5% to 4.5% by weight of the first powder coating composition.17. The method according to claim 1 wherein the substrate is aconductive substrate.
 18. The method according to claim 2 wherein thesubstrate is a conductive substrate.
 19. The method according to claim 1wherein the optional protective layer is present and wherein each powdercoating composition is heated separately.
 20. The method according toclaim 2 wherein each powder coating composition is heated separately.